An epitope associates with which part of an antigen receptor or antibody? a. the tail b. the heavy-chain constant regions only c. variable regions of a heavy chain and light chain combined d. the light-chain constant regions only

Video transcript

Welcome back. Let's look at our next problem blank. Is the specific region of the antibody where the episode binds the epa Tope is the site on antigen that gets recognized by a specific antibody. So let's kind of draw a rough sketch of an antibody here that sort of Y shape With four chains making it up. Okay and up here we have our binding sites specific to an antigen and that is what we're looking for. So the epic Tope on the antigen binds to these binding sites. These binding sites will recall from our content videos are called the Para Tope. So Choice A. Is the correct answer. Para Tope let's just walk briefly through the other choices. Choice B antigen. The antigen is not on the antibody binding to the antibody. So that's an easy one to eliminate. I see the fab region. The fab region is actually this lower part of the antibody down here and that's the portion of the chain that is constant. It doesn't change all antibodies. It's consistent from antibody to antibodies since that's not part of recognizing a specific antigen. So that is not involved in binding to the episode of the anti eliminate that and choice the heavy chain region. Um And that heavy chain part of the structure is down here on this constant portion. It's that guy um and highlighted instead down here in this constant portion there's some heavy chain and then the heavy chain also. Um We have a little bit of the outside here but that's not part of that specific binding site. So we can eliminate that choice confirming that correct answer of a Para Tope. So even if you couldn't remember that specific word, Para Tope, well they've got a clue. Since it reminds you of the word Epic Tope, you could go through and find the other three choices and realized they're not the binding sites to help you lead the way to Para Tope. If you've forgotten that word, thanks for watching, see you in the next video.